Electromagnetic device



March 5, 1946.

R.- s. G. TERRY ETAL 2,396,135

ELECTROMAGNETIC DEVICE Filed April so, 1943 2 Sheets-Sheet 1 59 I 52 54 l I I 59 5/ 4 I 1| If I I 1 mmMM- f/z imyi Attorr-wy R. s. G. TERRY EI'AL 2,396,135

March 5, 1946.

ELECTROMAGNETIC DEVICE Filed April 50, 194s 2 Sheets-Sheet 2 v 7 Attorney Patented Mar. 5, 1946 j UNITED STATES PATENT OFFICE,

ELECTROMAGNETIC DEVICE Robert Saint George Terry, New .Maiden, and

Rupert Evan Howard Carpenter,

Croydon, England South Application April 30, 1943, Serial No. 485,244 In Great Britain May 6, 1942 4 Claims. (01.179-114) device is driven mechanically and provides anelectrical output, as is the case with electromagnetic pick-ups for gramophones or vibratory magneto-electric generators.

The invention is more particularly concerned with the magnetic structure for such devices by means of which the fluxes are applied to the circuits carrying the polarising flux. In the simplest arrangement, there are two magnetic circuits carrying polarising flux and two carrying varying flux, and the magnetic limbs referred to carry the windings for the reversals or line currents. In such a case, there are two pairs of polepieces presented to the armature surfaces, each pair lying in one of the magnetic circuits carrying the varying flux, and one pole-piece of each of those pairs forms part of one of the magnetic circuits carrying the polarising flux, and the other pole-piece of each pair forms part of the other magnetic circuit carrying polarising flux. The windings carrying the reversals or line currents are connected to produce magneto-motive forces which cause fluxes to pass through the armature in opposite directions. 'When\ the fluxes tend to pass through the armature in opposite directions, the armature is urged from side to side and may be pivoted to permit such motion, or may be mounted so as to be capable of bodily movement in a straight line.

Some examples of various kinds of devices pro- Figure 4 is a central cross-section of a form of telephone receiver having an armature approximately rhombus-shaped; and

Figure 5 is a detailed perspective view of its armature.

In Figures 1 to 3, a form of telephone receiver in accordance with the invention i illustrated, but in this case the whole movement which is enclosed in a case consisting of an upper moulding 42 and a lower moulding 43, has four magnetic circuits for the polarising flux and four for the varying flux. There are in fact housed in the moulding four sets of upper laminations 44 and four sets of lower laminations 45. The armature is a magnetic diaphragm 4B, and the pole-pieces 41, of which there are eight in this case, terminate in faces parallel to the armature 4B. The latter is a stamping with four outwardly-projecting lugs 48, as seen in Figure 1, which are secured to insets 49 in the lower part of the moulding 43 by four screws 50. Thus the diaphragm is mounted to permit linear vibration along an axis normal to its plane. The lower half of the moulding 43 is formed with a moulded cavity 5|, and the upper half of the moulding 42 with an outlet 52 with its lower wall 53 perforated. The diaphragm 46 is sealed to the wall of the outlet 52 by means of a flexible ring 54. In this case, there are four upper magnets '55 and four lower magnets 56, each magnet being of right-angle shape as seen in Figure 1, and they are magnetised with their like poles adjacent to one set of stampings 44 as indicated by the letters NS in Figure 1. It will be appreciated that, in this case, there are four magnetic circuits in parallel for the polarising flux from the top magnets 55. and four magnetic circuits in parallel for the polarising flux for the lower magnets 56, the flux passing in the armature 46 horizontally as seen in Figure 2, from one pole-piece 41 to the adjacent pole-piece 41 on either side of it.

There are four limbs formed by separate laminations and shown'at 51, connecting points of substantially equal mean magnetic potential in the laminations 44 and 45. Each carries a winding 58 for the signal or line current. The four windings 58 are connected so that the fluxes at the gaps above the armature 46 are all increased at times that the flux at the gaps below the armature is decreased so that the armature is drawn as a unit upwardly and downwardly due to the signal currents.

The lower surfaces of the moulding 42 are all flush and the upper surfaces of the moulding 43 h are all flush, and the laminations 41 are of such a size] that their pole-faces are flush with the surfaces 01' the moulding, The two halves of the mouldings 42, 43 are secured together by bolts and nuts 59, and the correct spacing of the polefaces of the laminations at from the armature I6 is obtained by the insertion oi a spacing ring 80 between the two mouldings d2, 43, and of a thickness equal tothe thickness or the armature it together with the air gaps desired above and below the armature.

In Figures 4 and 5, a form of telephone receiver is shown in which the magnetic structure is very similar to that used in Figures 1 to 3 but employing only four pole-pieces and using a difterent shape of amnature. The armature it is of a lozenge-shape or in the form of a rhombus with the angles at the top and bottom relatively obtuse and with the points at the corners of the rhombus omitted, and provided with projectin rods 60, from each oi its obtuse corners. These rods N are formed by having a central plate 652 of the same shape as the laminations of the armature it but substantially thicker and in-- tended to reinforce the armature, the laminations of which are riveted on either side of the plate 82, li'he plate 62 is stamped with opposite projections corresponding to the pins til and these projections are swaged up from the-fiat to form the circular pins El, The pin SE at the bottom is secured by nuts to a flat spring 63, and the pin ii at the top is secured by nuts to the diaphragm 64 which is clamped around its edge. Thus armature I4 is mounted for linear vibration along an axis parallel with the rod ti passing through the narrow dimension of the armature. The magnets in this case are annular permanent magnets 65 which are magnetised so as to present opposite poles at opposite ends of a diameter as indicated by the letters NS in Figure 4. A mag- 'netic limb 6 connects pole-piece it with polepiece I2 and carries a winding 8, and a similar magnetic limb connects pole-piece M with polepiece l3 and carries a-winding E51,. The whole assembly is housed in a moulded casing 66 with a screw-on cover and earpiece bl. The windings 8, 9 are connected so as to produce magnetomotive forces tending to cause fluxes to pass through the armature in opposite directions, that is to say, if the varying flux passing from the pole-piece Ill to l2 at any instant is downwards,

that passing between the pole-pieces ii and it at that instant is upwards. Consequently, if the flux at the pole-piece I is increased, so is the flux at the pole-piece ll, while at the same instant the flux at the pole-pieces l2 and i3 is decreased. Therefore, the armature it is moved up and down bodily to provide a balanced linear movement which is imparted to the diaphragm it.

We claim:

1. An electromagnetic device comprising, in

combination, a magnetic armature mounted for linear vibration along a given axis, a pair of mag and polarizing means iorestablishing-a polarizing flux in another portion oi said armature through said second pair of pole-pieces, a pair of magnetic paths connecting the pole-pieces on one side of said armature with the pole-pieces on the opposite side of said armature, and a pair of windings surrounding said magnetic paths and producing magneto-motive forces tending to cause fluxes in the gaps of one pair or pole-pieces to be increased and the fluxes in the gaps of other pair of pole-pieces to be simultaneously de creased.

2. An electromagnetic device for the interconversion of electrical and mechanical vibra tions comprising, in combination, a magnetic ar= mature mounted for linear vibration along a given axis, a magnetic structure including polarizing means for establishing a polarizing flux in a por tlon of said armature and transversely oi said axis, a second magnetic structure including pols,- izing means for establishing a polarizing dun in another portion oi, said armature on the oppo site side of said armature from said first portion and transversely of said axis, a pair of magnetic limbs each connecting two points in said. magnetic structures, said points being at substantially the same mean magnetic potential derived from said polarizing means, and a winding sur rounding each or said magnetic limbs, said wind= ings being mutually connected to produce magneto-motive forces tending to cause the flux on one side of said armature to be increased at times when the'flux on the other side of said armature is decreased.

3. An electromagnetic device comprising, in combination, a diaphragm of magnetic material constituting an armature, means for mounting said diaphragm for linear vibration along an axis normal to the plane of the diaphragm, a magnetic structure including a pair of spaced pole-pieces presenting polar faces to one side of said dia phragm and including polarizing means for establishing a polarizing flux in said diaphragm between said pole-pieces, a second magnetic structure including a pair of pole-pieces presenting polar faces to the opposite side of said diaphragm and including polarizing means for establishing a polarizing flux in said diaphragm between said pole-pieces, a pair of magnetic limbs each connecting two points in said magnetic structures, said points being at substantially the same mean magnetic potential derived-from said polarizing means, and a winding surrounding each of said magnetic limbs, said windings being mutually connected so that one of said windings tends .to produce a magnetic flux transversely of the plane of said diaphragm between two polepieces located on opposite sides of said diaphragm, and the other winding tends to produce a magnetic flux transversely of the plane of said diaphragm between two poles on opposite sides of said diaphragm but in an opposite direction from said first transverse flux.

4. An electromagnetic device, comprising, in

combination, a magnetic armature having the shape of a rhombus, means for mounting said armature for linear vibration along the short axis thereof, four magnetic pole-pieces presenting polar faces'to the four faces of said rhombus, polarizing means for two of said pole-pieces positioned on opposite sides of said axis for establishing a polarizing flux through a portion of said armature transversely of said axis, second polarizingmeans for the remaining two of said pole pieces on opposite sides of said axis for estabtending to establish a flux in said armature parallel with said axis, and the other winding tending to establish a flux in said armature parallel with said axis but in a direction opposite to the flux 5 established by said first winding.

ROBERT SAINT GEORGE TERRY. RUPERT EVAN HOWARD CARPENTER. 

